Engine fuel vapor recovery system



July 9, 1968 R. D. WILLIAMS ETAL 3, 9

ENGINE FUEL VAPOR RECOVERY SYSTEM Filed March 28. 1966 FIG. 2.

INVENTORS ROBERT DWILLIAMS THOMAS G. WIER United States Patent 3,391,679 ENGINE FUEL VAPOR RECOVERY SYSTEM Robert D. Williams, La Grange, and Thomas G. Wier, Oak Lawn, Ill., assignors to International Harvester Company, Chicago, 11]., a corporation of New Jersey Filed Mar. 28, 1966, Set. No. 537,968 5 Claims. (Cl. 123136) ABSTRACT OF THE DISCLOSURE .An engine fuel vapor recovery system for utilizing vapors escaping from the fuel tank in the operation of a carbureted engine without affecting idle speed, which system includes a conduit providing fluid communication between the filler tube on the fuel tank and the carburetor, a valve interposed in the conduit and movable between a first position wherein the fuel tank is vented to the atmosphere and communication with the carburetor is blocked, and a second position wherein the fuel tank is in direct communication with the carburetor only, the valve being biased toward the first position at engine idle speed.

This invention relates to a fuel vapor recovery system for engines utilizing hydrocarbon fuels, such as gasoline, and to the abatement of air pollution resulting therefrom.

The operation of motor vehicles contributes markedly to the air pollution problem in large cities by the release of hydrocarbon to the atmosphere, either as unburned fuel via the exhaust system, or as evaporated fuel via the fuel supply system. Considering the fuel supply system, the fuel tank containing a large volume of volatile hydrocarbons possesses the capability of being a major contributor of polluting m'ssions through evaporation. With its vast potential air pollution, many solutions have been proposed which direct the vaporized fuel from the fuel tank to the carburetor where it can be inducted into the engine and burned. Such an approach will eliminate the pollution resulting from evaporation of fuel within the fuel tank, but will create, under certain conditions, a greater emission of pollutants released to the atmosphere through the exhaust system as unburned fuel. In addition, the unregulated induction of vaporized fuel from the fuel tank to the carburetor will result in erratic behavior of the engine when it is idling, i.e., the fuel air ratio at idle and the idle speed of the engine will depend upon the ambient temperature as well as the position of the throttle valve and the setting of the carburetor. When the engine is utilized to transmit power through an automatic transmission it is highly desirable that the idle speed of the engine remain relatively constant to avoid creeping as well as avoiding the imposition of stresses upon the components of the transmission which would occur when the engine is idling fast and the operator is compelled to apply the brakes to prevent movement of the vehicle.

It is, therefore, an object of the present invention to provide an engine fuel vapor recovery system which will substantially reduce the loss of vaporized fuel from the fuel tank through evaporation, and which will not affect the operation of the carburetor at slow idle.

It is also an object of this invention to provide an engine fuel vapor recovery system which will utilize the vapors emanating from the fuel tank in the combustion process of the engine whenever it is operating at a speed other than slow idle, but which will not increase the emission of pollutants from the exhaust system by pro ducing an over-rich mixture at slow idle.

It is another object of the present invention to pro- 3,391,679 Patented July 9, 1968 vide an engine fuel vapor recovery system which will increase the operating efficiency of the vehicle by utilizing the fuel evaporating from the fuel tank and which will permit a smooth and relatively constant engine idle speed.

These and other objects and many of the attendant advantages of the present invention will become more readily apparent from a perusal of the following description and the accompanying drawings, wherein:

FIGURE 1 is a schematic diagram of a preferred embodiment wherein the invention is utilized with an engine having an updraft carburetor;

FIGURE 2 is a detail view of a portion of FIG- URE 1 showing the throttle control linkage in its relationship with components of the system, and

FIGURE 3 is a detail view of a portion of FIGURE 1 illustrating the modification of a conventional fuel tank to adapt it to the system of this invention.

Referring now in detail to FIGURE 1, a conventional engine, shown in dotted lines and indicated generally at 10, is provided with an updraft carburetor 12 connected with an intake manifold 14. A throttle control rod 16 is pivotally connected to a lever 18 which is pivotally mounted on and operably connected to components of the carburetor for actuation thereof. A fuel tank 20 is in communication with the carburetor 12 through a conduit 22 through which liquid fuel is drawn from the fuel tank 20 by a fuel pump, not shown. The fuel tank is provided with a filler tube 24 which is adapted to receive in sealing engagement therewith, a cap 26. An opening or vent 28 is provided in the cap 26 and a check valve 30 is affixed to the cap positioned over the vent 28 in sealing engagement therewith to permit the flow of gas from the atmosphere into the tank while preventing the escape of fuel vapors from the tank into the atmosphere. The check valve 30 prevents the formation of a vacuum within the fuel tank 20' which would impair the pump ing of liquid fuel to the carburetor. A conduit 27 is inserted through the filler tube 24 and is in fluid communication with the space defined by the tube and cap 26. The other end of conduit 27 is connected to an inlet 29 of a three-way directional control, solenoid operated valve 30. The valve 30 has an outlet port 32 which is in fluid communication with the atmosphere and a second outlet port 34 which is connected through conduit 36 to the carburetor 12. The valve 30 is capable of assuming two positions, one in which the inlet port 29 is in fluid communication with the outlet port 34 and port 32 is closed, and the other in which inlet port 29 is vented to atmosphere through port 32 and the outlet port 34 is closed. A normally enclosed push button or contact switch 33 having a plunger 44 is connected to the coil of the solenoid through wire or conductor 40. Electrical power is supplied to the solenoid through wires 42 and 46 from any convenient source. In the resulting circuit, the switch 38 is in series with the solenoid. The switch 38 is mounted on the engine 19 in such a manner that the plunger 44 is depressed by the lever 18 whenever the throttle linkage is permitted to move the slow idle position, i.e., that position shown in dotted lines in FIG. 2. When the throttle lever is actuated to speed up the engine, the lever 18 is pivoted away from the plunger 44 as shown by the solid line position in FIGURE 2.

When the engine 10 is operating, electrical power is supplied to wires 42 and 46 and the solenoid will be actuated if the switch 38 is closed causing the valve 30 to connect the conduit 27 with the conduit 36. In this condition the fuel vapors present in the fuel tank 20 will be directed through the conduit 27, the valve 30 and the conduit 36 into the carburetor 12 where they will be inducted through the intake manifold 14 into the cylinders of the engine. However, whenever the throttle rod 16 1s permitted to move to idle position the lever 18 will rotate to the dotted line position shown in FIGURE 2 depressing the plunger 44 on the switch 38 and opening the circuit defined by wires 43, 42 and 46. With the circuit broken, the solenoid is de-activated causing valve 30 to shift thereby connecting the conduit 27 with the port 32 and venting the fuel vapors to atmosphere. Whenever the lever 18 is again moved away from its idle position, the plunger 44 on the switch 38 will be permitted to move outwardly establishing contact between wires 40, 42 and 46 and re-energizing the solenoid to shift the valve 30 so that conduits 27 and 36 are again in fiuid communication directing fuel vapors from the tank 20 to the carburetor 12. By utilizing the aforementioned arrangement of solenoid and normally closed contact switch, the tank 20 will be automatically vented to atmosphere wherever the ignition switch is opened or turned off.

It is therefore apparent that the present invention provides a means for utilizing the fuel vapors produced in the fuel tank of the vehicle due to vaporization in the cornbustion processes of the engine, but which disconnects or prevents the induction of such vapors into the engine whenever it is idling to preclude the possibility of an overly rich mixture or an increase in the idle speed. The system of the present invention thereby substantially reduces the loss of hydrocarbons to the atmosphere through evaporation of the fuel within the fuel tank and simultaneously decreases the emission of undesirable hydrocarbons to the atmosphere through the exhaust system which would result from an over rich mixture during idling.

While the foregoing description and drawing disclose a preferred embodiment of the present invention and the rinciple thereof, other embodiments of the invention employing the same or an equivalent principle may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the scope of the appended claims.

We claim:

1. In combination with an internal combustion engine having a carburetor, and a fuel tank, an improved conservation system adapted to minimize evaporative fuel losses without increasing undesirable emission from the engine during idle, comprising:

a conduit extending between the top of the fuel tank and the carburetor,

a valve interposed in said conduit and movable between a first position wherein said fuel tank is vented to atmosphere and communication with the carburetor is blocked, and a second position wherein said fuel tank is in direct communication with the carburetor only,

and valve actuating means for moving said valve to said first position when the engine is operating at idle speed, and to said second position when the engine is operating at faster than idle speed.

2. In a combination according to claim 1 and further comprising:

a filler tube on the fuel tank,

a cap capable of sealing engagement with said tube, and check valve means for permitting fluid fiow only from the atmosphere into the fuel tank.

3. In the combination according to claim 1 wherein a control linkage is operatively connected to the carburetor and said valve actuating means comprises:

a source of electric power,

a solenoid for moving said valve between said positions in response to being energized and deenergized, and a switch mounted for contact by said linkage when the engine is operating at idle speed, said switch and said solenoid being wired in series with said source such that the state of energization of said solenoid changes when said switch is contacted by said linkage to move said valve to said first position.

4. In the combination according to claim 3 wherein said switch is of the normally closed contact type and the solenoid maintains the valve in said second position when energized and shifts the valve to said first position when de-energized.

5. In the combination according to claim 1 wherein a control linkage is operatively connected to the carburetor and further comprising:

a filler tube on the fuel tank,

a cap capable of sealing engagement with said tube,

a check valve in said cap permitting flow of air only from the atmosphere into the fuel tank, and said valve actuating means includes:

a source of electrical power,

a solenoid for moving said valve between said first and second positions when de-energized and energized respectively, and

a normally closed contact switch mounted for contact by said linkage when the engine is operating at idle speed,

said switch and solenoid being wired in series with said source such that said solenoid is energized only when the engine is operating at a speed faster than idle speed.

References Cited AL LAWRENCE SMITH, Primary Examiner. 

